Many articles are available for cleaning surfaces of an object by abrasive action of an article rubbed by machine or hand on a surface. Surfaces may be two dimensional, flat or curved, or three dimensional shapes with complex combinations of curved and flat surfaces. Most conventional articles which provide the necessary cleaning, polishing and grinding action on such surfaces are stiff or rigid and fail to conform to complex curved surfaces.
Various flexible pads have been developed whereby abrasive grains have been adhesively secured to open cell foam substrates which are capable of absorbing fluids. For example, U.S. Pat. Nos. 2,780,533 and 2,650,158 each describe an abrasive pad comprising a porous or sponge rubber layer which includes a layer of abrasive grains adhered to one surface of the sponge layer.
Methods of making such open celled abrasive foam products are also disclosed in numerous prior art patents, with U.S. Pat. No. 3,701,703 being a typical example of such patents. U.S. Pat. No. 3,653,859 also disclose a low density open celled foam which is impregnated with a slurry formed of an adhesive and abrasive grain. A method of forming an abrasive article by heating an open celled meltable base and distributing abrasive particles over the surface is disclosed in U.S. Pat. No. 3,401,490.
U.S. Pat. No. 2,804,729 discloses the use of closed-cell foam rubber to form a sanding block. However, this configuration involves adhering two foam layers together along one edge only so that the layers may be pulled open to insert a portion of a folded abrasive sheet. A stiffening element, such as a metal plate, is placed between these layers providing increased rigidity.
It is also known in the prior art to secure rigid or flexible backings to open celled foams having a layer of abrasive particles. For example, U.S. Pat. No. 4,714,644 relates to a sanding pad having abrasive granules adhered to a stiff rectangular layer of cloth which is in turn adhered to a layer of open cell polyurethane foam. Similarly, U.S. Pat. No. 4,629,473 discloses an open cell foam which is laminated to a finished cloth backing. An adhesive coat is applied to the foam layer, then an electrostatic coating of abrasive grain is applied to the wet adhesive.
U.S. Pat. No. 4,606,154 relates to a coated abrasive material for use on abrasive belts. This material comprises a textile backing having an elastic intermediate layer, and an adhesive base binder with abrasive particles. The intermediate layer is a thin layer containing at least one elastic polymer, such as polyurethane, which has limited compressibility.
None of these prior art abrasive articles, however, disclose the use of a closed cell flexible polyvinyl chloride (PVC) foam having an abrasive coating on one or both sides so as to provide a flexible and durable abrasive material capable of conforming to even the most complex surfaces. Furthermore, this abrasive material will not absorb liquids usually associated with the cleaning, polishing and grinding operations.